A method for detecting weak joint defects at the interface of diffusion welding

Abstract

The invention provides a defect detecting method for a weak joint of a diffusion welding joint interface, aiming at solving the problem that the defect on the weak joint cannot be judged by the traditional ultrasonic wave detecting method. The defect detecting method comprises the steps of analyzing information concealed in Fourier transform spectrum phase of a weak joint defect signal in a frequency domain, and reflecting positive and negative wave Fourier transform spectrum phases as reference by utilizing an unwelded lower surface of an upper-layer sample; by judging the differences and similarities between the positive and negative wave Fourier transform spectrum phases reflected by a joint interface of a diffusion welding sample and the positive and negative wave Fourier transform spectrum phases reflected by the unwelded lower surface of the upper-layer sample, extracting defect phase jump information of the weak joint, establishing a phase jump function, and judging the defect of the weak joint according to the criterion. According to the defect detecting method for the weak joint of the diffusion welding joint interface, the defect of the weak joint can be correctly judged, and the problem that an ultrasonic wave detection method is difficult to judge the defect only according to a time domain signal is solved.

Description

technical field [0001] The invention relates to a method for detecting a welding interface, in particular to a method for detecting a weak joint defect at a diffusion welding connection interface. Background technique [0002] Diffusion welding is an advanced solid-phase welding method. The base metal does not need to be melted during welding, and the surfaces of the materials to be welded are in contact with each other. Under certain temperature and pressure, microscopic plastic deformation or microscopic The liquid phase expands the physical contact of the surface to be welded, and the welding method realizes the combination through the interdiffusion of atoms for a long time. Diffusion welding has the advantages of welding difficult-to-miscible materials, small surface plastic deformation, and uniform joint composition and structure. Typical defects of the diffusion bonding interface are lack of fusion, weak joints and microscopic holes. Weak joint defects seem to be we...

AI Technical Summary

Problems solved by technology

For diffusion welded joints of the same material, the ultrasonic waves produce very weak reflected waves on tiny weak joint defects; The interface also generates reflection waves, and the defect reflection waves are mixed with the interface reflection waves, making it difficult to distinguish and further increase the difficulty of detection. At present, there is no reliable detection method for weak joint defects

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